Method of key bitting



July 17, 1956 sw so 2,754,701

METHOD OF KEY BITTING Filed 001.- 20, 1954 FIGJ.

INVEN TOR. GUNNAR E. SWANSON A TTORNEV United States Patent METHOD OF KEY BITTING Gunnar E. Swanson, Middletown, Conn.

Application October 20, 1954, Serial No. 463,408

Claims. (Cl. 76-110) The invention relates to a method for bitting a key of the type having transverse generally V-shaped bitting notches along at least one longitudinal edge thereof. The centers of the notches are uniformly spaced longitudinally but the notches have difierent depths and different widths in accordance with the bitting pattern of the particular key. The invention relates more specifically to the making of keys wherein the widths of the deeper notches are greater than the average allotted space for each bitting, and wherein the different depths of the bitting notches on each side of any particular notch result in a bitting notch having a greater composite sweep on one side of the center of said notch than on the other side of the center of said notch.

The general prior practice for making a key of this type has been to cut each bitting notch separately with a cutter having a width at least as large as the width of the widest notch. The said width of the widest notch is sometimes greater than the notch spacing, and for this reason it has not previously been practicable to cut all notches simultaneously, excepting when a special cutter has been made to cut the specific arrangement of the bittings are required for a specific key. The angular sweep of one bitting notch on the key must meet the angular sweep of adjacent bitting notches, and it follows that the angular sweeps from the center of each bitting is dependent upon the depths of the bittings on each side. Should it be attempted to use mating cutters for varied bittings, it would be found that the tolerance factor and the required variety of cutters would rule against this for commercial practice. To have followed such procedure it would have been necessary to have available and to use an unreasonably large number of cutters of various widths and shapes for the bitting of a variety of differently bitted keys.

The general object of the present invention is to provide a method of key bitting which makes it possible to simultaneously form all bitting notches for a key or for a lot of similar keys without providing cutters of varying Widths and contours, all cutters being of the same width and contour notwithstanding the differing widths of the several bitting grooves. This avoids the cost of special cutters for specific bittings, and is far less expensive than the present method of cutting each bitting notch sepa I rately.

In the drawing I have shown schematically a key blank and a battery of cutters having uniform widths, the drawing illustrating the practice of the method by use of the said battery of cutters. It will be understood that the drawing is not to be construed as defining or limiting the scope of the invention, the claims forming a part of this specification being relied upon for that purpose.

Of the drawing:

Fig. 1 is a side view of a key blank such as is utilized in practicing the method of the invention.

Fig. 2 is a right end view of the blank shown in Fig. 1.

Fig. 3 is a schematic view of a battery of cutters adapted for cutting the blank shown in Figs. 1 and 2.

Fig. 4 is a side view of the key formed by the action of the battery of cutters on the blank.

Fig. 5 is a right end view of the key as shown in Fig. 4, this view also schematically illustrating the action of the cutters shown in Fig. 3 when such cutters are rotary milling cutters.

Fig. 6 is a side view of the key as shown in Fig. 4- together with a schematic view of lock tumblers engaged with the bitting thereof.

In the practice of the method of the invention, a key blank is initially provided, and this blank can be widely varied as to its general shape and as to its longitudinal fluting, if any, but in accordance with the invention it has at least one longitudinal edge which may be the upper edge. The blank is subjected along its said longitudinal edge to two notching operations the sequence of which is not essential as concerns the broader aspects of the invention. As shown in Fig. 1, there is a key blank 10 having a longitudinal edge 12, but the disclosed notches along the edge 12 are not necessarily present in the initial blank.

One notching operation is such as to tend to provide the blank along the said longitudinal edge 12 with a plurality of similar transverse V-shaped notches 14, 14. The edges of the notches are at suitable angles with respect to the longitudinal lines of the blank. The notches have a predetermined uniform longitudinal spacing with similar uniformly spaced areas 16, 16 which intervene between adjacent notches. The before-described notching operation may be prior to the other hereinafter described operation or subsequent thereto. The first described notching operation, when prior, results in complete notches 14, 14 as shown in Fig. 1, but when not prior the notches 14, 14 will be incomplete as hereinafter explained. For convenience of description it will be, assumed that the notches 14, 14 are formed first. The said notches may be formed simultaneously with the formation of the blank or by separate cutting operations.

For the other notching operation, there is provided a battery of relatively fixedly connected V-shaped cutters having uniform spacing and widths in the longitudinal direction, the spacing corresponding to the said uniform spacing of the intervening areas 16, 16. As shown, the blank 10 has five such areas and there are therefore five cutters in the battery, these cutters being designated respectively as 18, 20, 22, 24 and 26. The cutters have for convenience been described as V-shaped, but preferably and as shown they are somewhat flattened or rounded at the bottoms of the VS so that they are adapted to cut similarly shaped notches. The cutters are preferably so shaped that the edges of the notches cut thereby will be at angles which are about the same as the angles of the edges of the notches 14, 14 in the blank, whether such notches 14, 14 are formed previously or subsequently. Although the cutters 18, 20, 22, 24 and 26 have uniform widths they have various effective transverse depths with respect to a longitudinal reference line aa which may be regarded as having a fixed relationship with said cutters. In use, as hereinafter explained, the line a-a is brought into register with the upper edge 12 of the blank. In other words, the cutters extend to various extents below said relatively fixed reference line a-a, and in the particular example shown the cutter 26 merely extends to the said line.

The invention is not necessarily limited to cutters of any particular type, but as shown the cutters are milling cutters rigidly held in fixed relation to each other and locked adjacently on the spindle 28 of a key bitting machine, the said cutters being rotatable about the central longitudinal axis of said spindle. When the cutters are rotary milling cutters they have different radii which provide differences in effective depth below the reference line aa.

In performing the said other notching operation, the battery of cutters and the blank are relatively moved to cause the cutters to engage the blank at some or all of the intervening areas 16, 16 thereof with the center lines of the cutters registering with the center lines of said areas, irrespective of whether the notches 14, 14 have been previously formed or will be subsequently formed. Fig. shows schematically the engagement of the cutters with the blank, it being assumed that the cutters are milling cutters. It is further assumed that the axis 28 of the cutters is fixed and that the blank is moved beneath the cutters. It will be understood that the setting is such that the last-mentioned notches are cut to predetermined depths, with the reference in the depths of the several notches resulting from the use of cutters with established radii actuated into correct cutting relation to the blank. In setting the machine the reference line aa registers with the upper edge 12 of the blank during the cutting operation.

By reference to Fig. 4 it will be seen that the cutters 18, 20, 22 and 24 respectively cut transverse notches 32, 34, 36 and 38 of different depths and that the cutter 26 in this particular instance does no cutting as the key blank is shown as having the correct high bitting at the position of the said cutter 26. If as the result of tolerance in the making of the blank the bitting is too high at the last said position, the cutter 26 will make the necessary correction. For a different bitting pattern, all of the cutters may cut actual notches or one or more of the other cutters may be at a position having the correct high bitting. The cut portions of the areas 16, 16 are indicated in Fig. 4- by dotted lines at 16 16.

Inasmuch as the cutters engage the blank at the said areas 16, 16 thereof, the notches of varying depths formed by the several cutters cooperate with the notches 14, 14, whether formed previously or subsequently, to provide the required bitting notches 40, 42, 44 and 46 of the key. Inasmuch as the bitting notches are composites of the notches 14, 14 and of the notches formed by the cutters, they can have varying composite widths notwithstanding the uniform widths of the cutters. As shown, the bitting notches 42 and 46 are narrower than the corresponding cutters 20 and 24 and the bitting notches 40 and 44 are wider than the corresponding cutters 18 and 22.

As an example, the greater width of the low bitting notch 44 is due to the fact that it is adjacent the high bitting notches 42 and 46. For the proper control of the lock tumblers to be engaged by the key, the incline of the low bitting notch must extend beyond the points midway between the bitting centers until they join the inclines of the adjacent high bitting notches. In the particular case of the notch 44 the depth is such that the corresponding intervening area 16 has been entirely removed with the result that the edges of the two notches 14, 14 at opposite sides of the removed area constitute at least approximate continuations of the edges of the notch 36 formed by the cutter 22. A tolerance factor can be provided so that the lowest bitting notch will be several thousandths of an inch, or as required, above the points where the notches cut by the cutter constitute approximate continuations of the notches 14, 14.

While the cutters 18, 20, 22, 24 and 26 are preferably milling cutters, they may be cutters of other types. For example, they may be nipping cutters clamped in fixed relationship to each other and relatively moved transversely of the blank to form the required grooves. When nipping cutters are used, they may be identical in size and shape and the various effective depths below the reference line aa may be obtained by varying the settings of the cutters.

Alternatively, the bitting notches can be cut by an adjustable die mechanism having the male punch and female die portions designed to constitute several notching devices corresponding with the bitting notches. These notching devices are so designed as to be adjustable to variable cutting relationships with the respective male and female portions locked in correct positions for the desired bitting notching of a specific key. The adjustable die mechanism may be thus employed for making keys from the blanks 10, the notches 14, 14 being formed previously or subsequently as preferred.

The notches 14, 14 can be made by milling cutters set in tandem with the other cutters in the milling operation on a double spindle machine, so as to make one handling of key blanks in the conversion from blanks to keys. The notches 14, 14 are made either before or after the bitting notches by a separate set of cutters so as to complete the bitting of a key in one operation. Similarly, a secondary set of clippers or dies can provide the notches 14, 14 before or after the key bitting notches are made by the said clippers or dies for the desired keys.

Fig. 6 shows schematically the engagement of the key 30 with the tumblers 48, 50, 52, 54 and 56 of a lock, the tumblers 48, 50, 52 and 54 being variously positioned in accordance with depths of the bitting notches 40, 42, 44 and 46. The tumbler 56 may be regarded as engaged in a notch of zero depth. Fig. 6 shows in dotted lines the shapes that the notches formed by the cutters would have if the notches 14, 14 were not provided. It will be evident that a key having the said dotted line shape would be entirely inoperative for moving the tumblers.

When the cutters are milling cutters, it is necessary to provide only a small number of cutters having different diameters corresponding to possible bitting notch depths. When the cutters are nipping cutters or dies, only one set is necessary as the required differences in bitting notch depths can be obtained by properly setting the cutters or dies.

It has been stated that the sequence is not essential as concerns the broader aspects of the invention. However, there may be a distinct advantage in each sequence for particular circumstances or with particular types of key bitting mechanisms. In some instances it may be preferable to form the notches 14, 14 first, and in other instances it may be preferable to form the said notches 14, 14 last.

The invention claimed is:

1. The hereindescribed method of key bitting which comprises forming a key blank having at least one longitudinal edge at which transverse bitting notches are to be formed, providing a battery of relatively fixedly connected V-shaped cutters having uniform spacing and widths in the longitudinal direction and having various efiective transverse depths, and subjecting the blank to two notching operations, one notching operation being such as to tend to provide the blank along said longitudinal edge with a plurality of similar V-shaped notches uniformly spaced longitudinally and with a plurality of similar uniformly spaced intervening areas, and the other notching operation consisting in relatively moving said battery of cutters and said blank to cause the cutters to engage the blank at some or all of said intervening areas thereof with the center lines of the cutters registering with the center lines of said areas so that the several V- shaped cutters remove portions of the corresponding areas to form notches of various depths corresponding respectively to the effective depths of the cutters in the battery which last said notches are combined with the first said notches to provide a key having uniformly spaced V- shaped bitting notches with said various depths and with various widths.

2. The method as set forth in claim 1, wherein the second said notching operation is so related to the first said notching operation that at least one of the cutters entirely removes a corresponding intervening area of the blank and so that the edges of the two first said notches at opposite sides of the removed area constitute approximate continuations of the V-shaped edges of the notch formed by the said last said cutter.

3. The hereindescribed method of key bitting which comprises forming a key blank having at least one longitudinal edge at which transverse bitting notches are to be formed, providing a battery of relatively fixedly connected V-shaped milling cutters rotatable about an axis parallel with the longitudinal edge of the blank, said milling cutters having uniform spacing and widths in the iongitudinal direction and having various radii providing var-- ious effective transverse depths, and subjecting the blank to two notching operations, one notching operation being such as to tend to provide the blank along said longitudinal edge with a plurality of similar V-shaped notches uniformly spaced longitudinally and with a plurality of similar uniformly spaced intervening areas, and the other notching operation consisting in relatively moving said battery of milling cutters and said blank to cause the cutters to engage the blank at some or all of said intervening areas thereof with the center lines of the cutters registering with the center lines of said areas so that the several V-shaped cutters remove portions of the corresponding areas to form notches of various depths corresponding respectively to the effective depths of the cutters in the battery which last said notches are combined with the first said notches to provide a key having uniformly spaced V-shaped bitting notches with said various depths and With various widths.

4. The hereindescribed method of key bitting which comprises forming a key blank having an initial plurality of similar transverse V-shaped notches along one longitudinal edge thereof, said notches having a predetermined uniform longitudinal spacing with uniformly spaced areas intervening between adjacent notches, providing a battery of fixedly connected V-shaped cutters having uniform widths in the longitudinal direction which correspond to said uniform spacing of said areas and having various effective transverse depths, and subsequently to the formation of said notches relatively moving said battery of cutters and said blank to cause the cutters to engage the blank at some or all of said intervening areas thereof with the center lines of the cutters registering with the center lines of said areas so that the several V-shaped cutters remove portions of the corresponding areas to form notches of various depths corresponding respectively to the effective depths of the cutters in the battery which last said notches cooperate with the initial notches of the blank to provide a key having uniformly spaced V-shaped bitting notches with said various depths and with various widths.

5. The hereindescribed method of key bitting which comprises forming a key blank having at least one longi tudinal edge at which transverse bitting notches are to be formed, providing a battery of fixedly connected V- shaped milling cutters rotatable about an axis parallel with the longitudinal edge of the blank, said milling cutters having uniform spacing and widths in the longitudinal direction and having various radii providing various etlective transverse depths; relatively moving said battery of milling cutters and said blank to cause the cutters to engage the blank and form notches of various depths therein corresponding respectively to the spacing and effective depths of the cutters in the battery, and subsequently subjecting the blank to a notching operation which provides the blank along said longitudinal edge with portions of a plurality of similar V-shaped notches uniformly spaced longitudinally and with a plurality of similar uniformly spaced intervening areas which intervening areas have their center lines in register with the center lines of the notches formed by the cutters so that said portions of the last said notches can be combined with said notches formed by the cutters to provide a key having uniformly spaced V-shaped bitting notches with said various depths and with various widths.

References Cited in the file of this patent UNITED STATES PATENTS 842,903 Napier Feb. 5, 1907 1,537,049 Vives May 5, 1925 1,576,908 Hartig Mar. 16, 1926 1,932,223 Lundquist Oct. 24, 1933 2,005,497 Falk June 18, 1935 2,677,423 Uher May 4, 1954 

